Screw-on cap closures are known in the metal beverage container art. An open end of the container may be opened and resealed using the screw-on closure cap. A number of references teach such screw-on closure caps with many different features achieving differing levels of success.
One method involves production of a can body having a necked-in upper portion terminating at a threaded open end. These containers generally resemble screw top bottles. The threads are typically mechanically formed using the excess metal at the open end of the can body. Formation of the threads, however, is a difficult manufacturing process.
Recently, lug-type resealable closure systems have been introduced into the beverage market. Such closures are described in U.S. Pat. No. 6,082,944, issued to Bachman et al. These closure systems include a set of elongated lugs located about the container at an upper neck portion. These lugs cooperate with a second set of inwardly extending lug members formed in a curled rim of a cap member. When the cap member is attached to the upper neck portion, the cooperating lug members draw the cap against a curled seal rim of the container. These closure systems overcome some of the drawbacks of the threaded closures because the relatively expensive operation of threading the wall of the container body is avoided, and these types of closure systems enable the use of a container which has a very short skirt and therefore requires less material than the relatively long-skirted caps usually employed as a screw closure.
However, these types of closures often will not seal the open end of the container particularly well. Several cap variations have been introduced with mixed results. To date, no lug-type cap closure has performed well enough to meet a wide variety of end user requirements. Therefore, a lug-type closure system that can be reliably manufactured while overcoming the problems associated with fully threaded closures while providing a resealable closure cap is needed.
The present invention is provided to solve the problems discussed above and other problems, and to provide advantages and aspects not provided by prior closure caps of this type. A full discussion of the features and advantages of the present invention is deferred to the following detailed description, which proceeds with reference to the accompanying drawings.